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数据加载中……

qthread QNetworkAccessManager QEventLoop

进程通过QNetworkAccessManager 进行http请求。代码如下:

//qhttp.h
#ifndef QHTTP_H
#define QHTTP_H

#include 
<QtGui/QWidget>
#include 
"ui_qhttp.h"
#include 
<QNetworkAccessManager>
#include 
<QUrl>

class QPushButton;
class QDialogButtonBox;
class QNetworkReply;

class qhttp : public QWidget
{
    Q_OBJECT

public:
    qhttp(QWidget 
*parent = 0);
    
~qhttp();

    
void startRequest(QUrl url);

private:
    Ui::qhttpClass ui;

    QPushButton 
*downloadButton;
    QDialogButtonBox 
*buttonBox;

    QUrl url;
    QNetworkAccessManager qnam;
    QNetworkReply 
*reply;

private slots:
    
void downloadFile();
    
void httpFinished();
}
;

#endif // QHTTP_H


//qhppt.cpp
#include "qhttp.h"
#include 
<QtGui>
#include 
<QtNetwork>
#include 
<iostream>

using namespace std;

qhttp::qhttp(QWidget 
*parent)
    : QWidget(parent)
{
    ui.setupUi(
this);

    downloadButton 
= new QPushButton(tr("Download"));
    downloadButton
->setDefault(true);


    buttonBox 
= new QDialogButtonBox;
    buttonBox
->addButton(downloadButton, QDialogButtonBox::ActionRole);

    connect(downloadButton, SIGNAL(clicked()), 
this, SLOT(downloadFile()));

    QVBoxLayout 
*mainLayout = new QVBoxLayout;
    mainLayout
->addWidget(buttonBox);
    setLayout(mainLayout);
}


qhttp::
~qhttp()
{

}


void qhttp::downloadFile()
{
    cout
<<"downloadFile"<<endl;
    url 
= "http://www.baidu.com/";
    startRequest(url);
}


void qhttp::startRequest(QUrl url)
{
    cout<<"startRequest"<<endl;
    reply = qnam.get(QNetworkRequest(url));
    connect(reply, SIGNAL(finished()), this, SLOT(httpFinished()));
}

void qhttp::httpFinished()
{
    cout
<<"httpFinished"<<endl;
    
if(reply->error())
    
{
        cout
<<"error:"<<qPrintable(reply->errorString())<<endl;
    }

    
else
    
{
        cout
<<"right"<<endl;
    }

}



但当主进程开辟线程来执行http请求时,却无法成功。

//qhttp.h
#ifndef QHTTP_H
#define QHTTP_H

#include <QtGui/QWidget>
#include "ui_qhttp.h"
#include <QNetworkAccessManager>
#include <QUrl>

class QPushButton;
class QDialogButtonBox;
class QNetworkReply;
class qhttpThread;

class qhttp : public QWidget
{
    Q_OBJECT

public:
    qhttp(QWidget *parent = 0);
    ~qhttp();

    void startRequest(QUrl url);

private:
    Ui::qhttpClass ui;

    QPushButton *downloadButton;
    QDialogButtonBox *buttonBox;

    QUrl url;
    QNetworkAccessManager qnam;
    QNetworkReply *reply;
    qhttpThread *httpthread;

private slots:
    void downloadFile();
    void httpFinished();
};

#endif // QHTTP_H



//qhttp.cpp
#include "qhttp.h"
#include "qhttpThread.h"
#include <QtGui>
#include <QtNetwork>
#include <iostream>

using namespace std;

qhttp::qhttp(QWidget *parent)
    : QWidget(parent)
{
    ui.setupUi(this);

    downloadButton = new QPushButton(tr("Download"));
    downloadButton->setDefault(true);


    buttonBox = new QDialogButtonBox;
    buttonBox->addButton(downloadButton, QDialogButtonBox::ActionRole);

    connect(downloadButton, SIGNAL(clicked()), this, SLOT(downloadFile()));

    QVBoxLayout *mainLayout = new QVBoxLayout;
    mainLayout->addWidget(buttonBox);
    setLayout(mainLayout);
}

qhttp::~qhttp()
{

}

void qhttp::downloadFile()
{
    cout<<"downloadFile"<<endl;
    //url = "http://www.baidu.com/";
    //startRequest(url);


    httpthread = new qhttpThread(this);
    httpthread->start();

}

void qhttp::startRequest(QUrl url)
{
    cout<<"startRequest"<<endl;
    reply = qnam.get(QNetworkRequest(url));
    connect(reply, SIGNAL(finished()), this, SLOT(httpFinished()));
}

void qhttp::httpFinished()
{
    cout<<"httpFinished"<<endl;
    if(reply->error())
    {
        cout<<"error:"<<qPrintable(reply->errorString())<<endl;
    }
    else
    {
        cout<<"right"<<endl;
    }
}

此时会出现程序运行崩溃、没有执行http请求任务等情况。
简单说一下注意事项:
1  线程中的run函数返回后线程即结束,根本无法等到reply的finished信号。因此需要加入QEventLoop来挂起线程。

2  通过connect设置信号槽,需要QObject的支持,因此在构造函数里与头文件中需要修改代码。

最终的修改代码如下:
//qhttpThread.h
#ifndef QHTTPTHREAD_H_
#define QHTTPTHREAD_H_

#include <QThread>
#include <QObject>
#include <QNetworkAccessManager>
#include <QUrl>

class QNetworkReply;
class QEventLoop;

class qhttpThread : public QThread {
    Q_OBJECT
public:
    qhttpThread(QObject *parent = 0);
    virtual ~qhttpThread();

    void run();

private:
    QUrl url;
    QNetworkAccessManager qnam;
    QNetworkReply *reply;
    QEventLoop *loop;

    void startRequest(QUrl url);

private slots:
    void httpFinished();
};

#endif /* QHTTPTHREAD_H_ */




//qhttpThread.cpp
#include "qhttpThread.h"
#include <QtNetwork>
#include <QEventLoop>
#include <iostream>
using namespace std;

qhttpThread::qhttpThread(QObject *parent) : QThread(parent) {
    // TODO Auto-generated constructor stub

}

qhttpThread::~qhttpThread() {
    // TODO Auto-generated destructor stub
}

void qhttpThread::run()
{
    cout<<"run"<<endl;
    url = "http://www.baidu.com/";
    startRequest(url);


    exec();
    cout<<"run end"<<endl;
}

void qhttpThread::startRequest(QUrl url)
{
    cout<<"startRequest"<<endl;

    loop = new QEventLoop;
    reply = qnam.get(QNetworkRequest(url));
    connect(reply, SIGNAL(finished()), this, SLOT(httpFinished()));

    loop->exec();
    cout<<"startRequest end"<<endl;
}

void qhttpThread::httpFinished()
{
    cout<<"httpFinished"<<endl;
    if(reply->error())
    {
        cout<<"error:"<<qPrintable(reply->errorString())<<endl;
    }
    else
    {
        cout<<"right"<<endl;
    }
    loop->quit();
}

这样,就可以对http进行请求了。

但在真正的执行中,当关闭界面程序时出现弹出框,提示:This application has requested the Runtime to terninate it in an unusual way.
原因还在查找中。

posted on 2011-01-04 09:28 seahouse 阅读(3624) 评论(0)  编辑 收藏 引用 所属分类: Qt


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